SAGA, Japan - A car plunged into a crowd of spectators at a drift event in southwestern Japan on Sunday, leaving four men injured including one in critical condition, police said.

A man in his 40s was unconscious after suffering a traumatic brain injury and another man in his 20s had a broken jaw, while the driver in his 20s hurt his neck and a man in his 30s in the passenger seat sustained a chest injury.

About 100 people were gathered in the ski resort parking lot where the accident occurred.

The police are investigating whether proper safety measures were in place for the event in Saga Prefecture organized by local auto sales and repair company Carpit Morinaga.

Junpei Morinaga, president of the company, said he felt a sense of responsibility and never thought such an accident could occur.

The injured spectators were from Saga and the two men in the car were from adjacent Nagasaki Prefecture.

A total of 66 vehicles took part in the event showcasing rear sliding driving techniques. Japan is a birthplace of drifting as a sport.

The first international drifting competition endorsed by the International Automobile Federation, or FIA, was held in late September through early October in Japan.

At a motorsport circuit in Utsunomiya, a 35-year-old woman was seriously injured during a drifting competition last year, as one of the wheels of a car came off and hit her during a practice session. She later died in a hospital.